Hi,
there are two different products regarding rebar detailing available
-SOFiSTiK Reinforcement Detailing.
This plug-in adds lots of features to the available Revit features to create shop drawings. It doesn't require a database.
-SOFiSTiK Reinforcement Generation requires a CDB file. Which represents the database and contains besides lots of other things all of your project relevant analysis and design information. To generate the CDB you'll need the SOFiSTiK FEA package.
It'S worth checking the online tutorial about the SOFiSTiK BIM Workflow to get an idea about all necessary steps. It shows not only how to generate a 3D rebar proposal based on the design results in Revit at the very end. Also, important things such as loading, mapping, exporting are part of it.
http://www.sofistik.de/documentation/2018/en/tutorials/BIM-building/BIM/bim-t1.html1
Just recently SOFiTiK released a new extension. The SOFiSTiK Analysis + Design for Revit 2019 which allows you to perform the analysis and design straight forward in Revit. There will be a free webinar about the plugin in two weeks.
https://www.sofistik.com/products/bim-cad/analysis-design-for-revit/
Guido